Electrocoat composition and process replacing phosphate pretreatment

ABSTRACT

An aqueous electrodeposition coating composition comprising a cathodically depositable binder, the binder comprising an amine-functional phosphorylated resin, provides corrosion protection equivalent to that obtained by the conventional phosphate pretreatment-electrodeposition coating process.

FIELD OF THE DISCLOSURE

The invention relates to electrocoat coating compositions, methods ofpreparing them, methods of electrodeposition of coatings onto aconductive substrate, and electrodeposited coatings.

BACKGROUND OF THE DISCLOSURE

The statements in this section merely provide background informationrelated to this disclosure and may not constitute prior art.

Industrial coating of metal articles that will be used in corrosiveenvironments may include application of one or more inorganic andorganic treatments and coatings. Painting systems (“paint shops”) inautomotive assembly plants are large, complex, and expensive. Metalautomotive vehicle bodies (the “body-in-white”) and parts, for instance,are given a many-step treatment of cleaning in one or more cleaningbaths or spray tanks, application of an aqueous phosphate coatingmaterial as a metal pretreatment step in a phosphating bath, thenvarious rinses and additional finishing treatments, such as described inClaffey, U.S. Pat. No. 5,868,820. The phosphating pre-treatment stepsare undertaken to improve corrosion resistance of the metal and adhesionof subsequent coatings to the metal. The cleaning and phosphating stepsmay have 10 or 12 individual treatment stations of spray equipment ordip tanks.

An electrodeposition coating (“electrocoat”) is applied after thepretreatment steps to the metal vehicle body. Electrocoat baths usuallycomprise an aqueous dispersion or emulsion of a principal film-formingepoxy resin (“polymer” and “resin” are used interchangeably in thisdisclosure), having ionic stabilization in water or a mixture of waterand organic cosolvent. In automotive or industrial applications forwhich durable electrocoat films are desired, the electrocoatcompositions are formulated to be curable (thermosetting) compositions.This is usually accomplished by emulsifying with the principalfilm-forming resin a crosslinking agent that can react with functionalgroups on the principal resin under appropriate conditions, such as withthe application of heat, and so cure the coating. Duringelectrodeposition, coating material containing the ionically-chargedresin having a relatively low molecular weight is deposited onto aconductive substrate by submerging the substrate in the electrocoat bathand then applying an electrical potential between the substrate and apole of opposite charge, for example, a stainless steel electrode. Thecharged coating material migrates to and deposits on the conductivesubstrate. The coated substrate is then heated to cure or crosslink thecoating.

One of the advantages of electrocoat compositions and processes is thatthe applied coating composition forms a uniform and contiguous layerover a variety of metallic substrates regardless of shape orconfiguration. This is especially advantageous when the coating isapplied as an anticorrosive coating onto a substrate having an irregularsurface, such as a motor vehicle body. The even, continuous coatinglayer over all portions of the metallic substrate provides maximumanticorrosion effectiveness. The phosphate pre-treatment, however, hasup to now been an indispensable step in protecting against corrosion forautomotive vehicle bodies. McMurdie et al., U.S. Pat. No. 6,110,341teaches that hydrocarbyl phosphate and phosphonic acid esters, which mayinclude polyepoxide linking groups, can be incorporated intoelectrodeposition baths in amounts of up to 500 ppm on total bath weightfor improved corrosion protection. Examples including phenylphosphonicacid were reported to have a modest increase in corrosion protectionover untreated steel panels.

SUMMARY OF THE DISCLOSURE

We disclose a composition and process for electrodepositing anelectrocoat coating on a metal substrate, which may be an unphosphatedmetal substrate (that is, a metal substrate that has not undergone aphosphate pretreatment) in which the electrocoat coating providesexcellent corrosion protection. Elimination of the steps and equipmentfor the phosphating pretreatment process permits a major cost savings inconstruction of a new paint shop, as well as a simplification and costsavings in operating paint shops now in automotive manufacturing plants.

The process uses an aqueous electrocoat coating composition, also calledan electrocoat bath, with a binder comprising a cathodicallyelectrodepositable resin having at least one phosphorous-containinggroup

in which X is a hydrogen, a monovalent hydrocarbon group (i.e.,hydrocarbyl group), an alkyl group such as an aminoalkyl group, an arylgroup, an alkylaryl group, an arylalkyl group, or an oxygen atom havinga single covalent bond to the phosphorous atom, and each oxygen atom hasa covalent bond to a hydrogen atom, an alkyl group, an aryl group, analkylaryl group, an arylalkyl group, or the cathodicallyelectrodepositable resin, with the caveat that at least one oxygen atomhas a covalent bond to the cathodically electrodepositable resin. Thealkyl groups may be cycloalkyl groups. The alkyl and aryl groups may behydrocarbyl groups or may include heteroatoms. For convenience, “resin”is used in this disclosure to encompass resin, oligomer, and polymer,and the cathodically electrodepositable resin having thephosphorous-containing group will be referred to as an amine-functionalphosphorylated resin. “Binder” refers to the film-forming components ofthe coating composition. Typically the binder is thermosetting orcurable.

In one embodiment, the amine-functional phosphorylated resin comprisesan amine-functional monophosphate ester or monophosphonic acid ester ofa polyepoxide resin. In another embodiment, the amine-functionalphosphorylated resin comprises an amine-functional diphosphate ester,triphosphate ester, or diphosphonic acid ester of a polyepoxide resin.In other embodiments, the amine-functional phosphorylated resin includesa combination of these esters. The remaining oxygens on the phosphorousatom that are not covalently bound between the resin and the phosphorousatom may also be esterified. In certain embodiments, at least one P—OHgroup remains unesterified; that is, the phosphorous containing grouphas at least one P—OH group.

In various embodiments, the amine-functional phosphorylated resin hasone phosphorous atom or a plurality of phosphorous atoms. Theamine-functional phosphorylated resin may be prepared using apolyepoxide extended by reaction with one or more extenders, an extenderbeing a material having at least two active hydrogen-containing groups.

In certain embodiments, the amine-functional phosphorylated resin may befrom about 0.01 to about 99% by weight of the total binder in theelectrodeposition coating composition. Among these embodiments are thosein which the amine-functional phosphorylated resin is from about 1 toabout 90% by weight of total binder in the electrodeposition coatingcomposition and those in which the amine-functional phosphorylated resinis from about 5 to about 80% by weight of total binder in theelectrodeposition coating composition. In certain embodiments, thebinder comprises a crosslinker for the amine-functional phosphorylatedresin. In certain embodiments, the binder comprises a secondamine-functional resin other than the amine-functional phosphorylatedresin. In any of these embodiments, the binder may also comprises acrosslinker which reacts during cure of the electrodeposited coatinglayer with the amine-functional phosphorylated resin, the secondamine-functional resin, or both.

We also disclose a method of coating an electrically conductivesubstrate, such as a metal automotive vehicle body or part, whichcomprises placing the electrically conductive substrate into the aqueouselectrodeposition coating composition having a binder comprising anamine-functional phosphorylated resin salted with an acid and, using theelectrically conductive substrate as the cathode, passing a currentthrough the aqueous electrodeposition coating composition to deposit acoating layer comprising the binder onto the electrically conductivesubstrate. The deposited coating layer may then be cured to a curedcoating layer. Subsequent coating layers may be applied on the(optionally cured) electrodeposited coating layer. For example, theelectrodeposited coating layer may be a primer layer and other layerssuch as an optional spray-applied primer surfacer and a topcoat layer ortopcoat layers (e.g., a colored basecoat layer and a clearcoat layer)may be applied over the electrodeposited coating layer.

In one embodiment of the method, the electrically conductive substrateis unphosphated before it is coated with an electrodeposited coatingcomprising the phosphorylated resin; that is, the substrate is free of aphosphate pre-treatment.

In one embodiment of the method, a metal automotive vehicle body iscleaned, and the cleaned metal automotive vehicle body iselectrodeposited with an aqueous coating composition comprisingamine-functional phosphorylated resin salted with an acid. Thus, nophosphate pretreatment is used. The binder of the electrocoat coatingcomposition may include a second amine-functional resin that does nothave phosphorous-containing groups, and generally a crosslinker reactivewith one or both amine-functional resins is included in the coatingcomposition so that the electrodeposited coating layer may be cured.

A coated, electrically conductive substrate comprises an electricallydeposited coating layer on the substrate, the electrically depositedcoating layer comprising a cured coating formed from a binder comprisingan amine-functional phosphorylated resin. In various embodiments, thebinder further comprises a crosslinker reactive with the phosphorylatedepoxy resin, a second resin such as previously described, or both thatreacts during cure to form the cured coating.

By making the phosphorylated resin electrodepositable, a greater amountof the phosphorous-containing groups can be incorporated into thecoating composition, resulting in significant improvement in corrosionprotection over untreated, particularly unphosphated, metallicsubstrates such as cold rolled steel.

“A,” “an,” “the,” “at least one,” and “one or more” are usedinterchangeably to indicate that at least one of the item is present; aplurality of such items may be present. Other than in the workingexamples provides at the end of the detailed description, all numericalvalues of parameters (e.g., of quantities or conditions) in thisspecification, including the appended claims, are to be understood asbeing modified in all instances by the term “about” whether or not“about” actually appears before the numerical value. “About” indicatesthat the stated numerical value allows some slight imprecision (withsome approach to exactness in the value; approximately or reasonablyclose to the value; nearly). If the imprecision provided by “about” isnot otherwise understood in the art with this ordinary meaning, then“about” as used herein indicates at least variations that may arise fromordinary methods of measuring and using such parameters. In addition,disclosure of ranges includes disclosure of all values and furtherdivided ranges within the entire range.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

A metal substrate, which may be unphosphated, is electrocoated with anaqueous electrocoat coating composition having a binder comprising anamine-functional phosphorylated resin. The amine-functionalphosphorylated resin is salted with an acid. The electrodepositedcoating layer may be cured and may be overcoated with one or moreadditional coating layers. The amine-functional phosphorylated resin hasat least one covalently bonded, phosphorous-containing group having astructure

in which X is a hydrogen, a monovalent hydrocarbon group, an alkyl groupsuch as an aminoalkyl group, an aryl group, an alkylaryl group, anarylalkyl group, or an oxygen atom singly bonded to the phosphorousatom, and each oxygen atom has a covalent bond to a hydrogen atom, analkyl group, an aryl group, an alkylaryl group, an arylalkyl group, orthe cathodically electrodepositable resin, with the caveat that at leastone oxygen atom has a covalent bond to the cathodicallyelectrodepositable resin. In each case, an alkyl group may be acycloalkyl group.

The amine-functional phosphorylated resin may be prepared using anyresin or polymerizable monomer that may be esterified with thephosphorous-containing group. Electrocoat coating binders often includeepoxy resins, and the amine-functional phosphorylated resin may, forexample, be an epoxy resin.

An amine-functional phosphorylated epoxy resin may be prepared invarious ways. In a first way, an amine-functional phosphorylated epoxyresin may be prepared by reaction of an epoxide-functional orhydroxyl-functional epoxy resin with a —P(OR)₂═O group-containing acidor acid derivative, with at least one R being a hydrogen atom or a loweralkyl group (by which we mean an alkyl group having one to four carbonatoms), particularly methyl, ethyl, propyl, isopropyl, isobutyl, butyl,or tert-butyl, that can be transesterified, such as phosphoric acid, amono- or diester of phosphoric acid, hypophosphoric acid, a monoester ofhypophosphoric acid, alkyl- or arylphosphonic acid, a monoester ofalkyl- or arylphosphonic acid, and combinations of these. Phosphoricacid or a source of phosphoric acid that used in the reaction may benonaqueous phosphoric acid, 85% in water, a more dilute aqueousphosphoric acid, pyrophosphoric acid, or polyphosphoric acid. Othersuitable phosphoric acid sources are described in Campbell et al., U.S.Pat. No. 4,397,970, incorporated herein by reference. Theepoxide-functional resin has at least one epoxide or hydroxyl group forreaction with the phosphorous-containing acid or acid derivative and haseither an amine group or a further group (which may also be an epoxidegroup) for reaction with a compound containing an amine group.

Suitable, nonlimiting examples of polyepoxide resins that may be reactedwith the —P(OR)₂═O group-containing acid or acid derivative includeepoxy resins with a plurality of epoxide groups, such as diglycidylaromatic compounds such as the diglycidyl ethers of polyhydric phenolssuch as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A),2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4′-dihydroxybenzophenone,dihydroxyacetophenones, 1,1-bis(4hydroxyphenylene)ethane,bis(4-hydroxyphenyl)methane, 1,1-bis(4hydroxyphenyl)isobutane,2,2-bis(4-hydroxy-tert-butylphenyl)propane,1,4-bis(2-hydroxyethyl)piperazine,2-methyl-1,1-bis(4-hydroxyphenyl)propane,bis-(2-hydroxynaphthyl)methane, 1,5-dihydroxy-3-naphthalene, and otherdihydroxynaphthylenes, catechol, resorcinol, and the like, includingdiglycidyl ethers of bisphenol A and bisphenol A-based resins having astructure

wherein Q is

R is H, methyl, or ethyl, and n is an integer from 0 to 10. In certainembodiments, n is an integer from 1 to 5. Also suitable are thediglycidyl ethers of aliphatic diols, including the diglycidyl ethers of1,4-butanediol, cyclohexanedimethanols, ethylene glycol, propyleneglycol, diethylene glycol, dipropylene glycol, triethylene glycol,tripropylene glycol, polypropylene glycol, polyethylene glycol,poly(tetrahydrofuran), 1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol,1,6-hexanediol, 2,2-bis(4-hydroxycyclohexyl)propane, and the like.Diglycidyl esters of dicarboxylic acids can also be used aspolyepoxides. Specific examples of compounds include the diglycidylesters of oxalic acid, cyclohexanediacetic acids,cylcohexanedicarboxylic acids, succinic acid, glutaric acid, phthalicacid, terephthalic acid, isophthalic acid, naphthalene dicarboxylicacids, and the like. A polyglycidyl reactant may be used, preferably ina minor amount in combination with diepoxide reactant. Novolac epoxiesmay be used as a polyepoxide-functional reactant. The novolac epoxyresin may be selected from epoxy phenol novolac resins or epoxy cresolnovolac resins. Other suitable higher-functionality polyepoxides areglycidyl ethers and esters of triols and higher polyols such as thetriglycidyl ethers of trimethylolpropane, trimethylolethane,2,6-bis(hydroxymethyl)-p-cresol, and glycerol; tricarboxylic acids orpolycarboxylic acids. Also useful as polyepoxides are epoxidized alkenessuch as cyclohexene oxides and epoxidized fatty acids and fatty acidderivatives such as epoxidized soybean oil. Other useful polyepoxidesinclude, without limitation, polyepoxide polymers such as acrylic,polyester, polyether, and epoxy resins and polymers, and epoxy-modifiedpolybutadiene, polyisoprene, acrylobutadiene nitrile copolymer, or otherepoxy-modified rubber-based polymers that have a plurality of epoxidegroups.

The polyepoxide resin may be reacted with an extender to prepare apolyepoxide resin having a higher molecular weight having beta-hydroxyester linkages. Suitable, nonlimiting examples of extenders includepolycarboxylic acids, polyols, polyphenols, and amines having two ormore amino hydrogens, especially dicarboxylic acids, diols, diphenols,and diamines. Particular, nonlimiting examples of suitable extendersinclude diphenols, diols, and diacids such as those mentioned above inconnection with forming the polyepoxide; polycaprolactone diols, andethoxylated bisphenol A resins such as those available from BASFCorporation under the trademark MACOL®. Other suitable extendersinclude, without limitation, carboxy- or amine-functional acrylic,polyester, polyether, and epoxy resins and polymers. Still othersuitable extenders include, without limitation, polyamines, includingdiamines such as ethylenediamine, diethylenetriamine,triethylenetetramine, dimethylaminopropylamine, dimethylaminobutylamine,diethylaminopropylamine, diethylaminobutylamine, dipropylamine, andpiperizines such as 1-(2-aminoethyl)piperazine, polyalkylenepolyaminessuch as triethylenetetramine, tetraethylenepentamine,pentaethylenehexamine, tripropylenetetramine, tetrapropylenepentamine,pentapropylenehexamine, N,N′-bis(3-aminopropyl)ethylenediamine,N-(2-hydroxyethyl)propane-1,3-diamine, and polyoxyalkylene amines suchas those available from BASF AG under the trademark POLYAMIN® or fromHuntsman under the trademark JEFFAMINE®.

A monofunctional reactant may optionally be reacted with the polyepoxideresin and the extender or after reaction of the polyepoxide with theextender to prepare an epoxide-functional resin. Suitable, nonlimitingexamples of monofunctional reactants include phenol, alkylphenols suchas nonylphenol and dodecylphenol, other monofunctional, epoxide-reactivecompounds such as dimethylethanolamine and monoepoxides such as theglycidyl ether of phenol, the glycidyl ether of nonylphenol, or theglycidyl ether of cresol, and dimer fatty acid.

Useful catalysts for the reaction of the polyepoxide resin with theextender and optional monofunctional reactant include any that activatean oxirane ring, such as tertiary amines or quaternary ammonium salts(e.g., benzyldimethylamine, dimethylaminocyclohexane, triethylamine,N-methylimidazole, tetramethyl ammonium bromide, and tetrabutyl ammoniumhydroxide.), tin and/or phosphorous complex salts (e.g., (CH₃)₃SNI,(CH₃)₄PI, triphenylphosphine, ethyltriphenyl phosphonium iodide,tetrabutyl phosphonium iodide) and so on. It is known in the art thattertiary amine catalysts may be preferred with some reactants. Thereaction may be carried out at a temperature of from about 100° C. toabout 350° C. (in other embodiments 160° C. to 250° C.) in solvent orneat. Suitable solvents include, without limitation, inert organicsolvent such as a ketone, including methyl isobutyl ketone and methylamyl ketone, aromatic solvents such as toluene, xylene, Aromatic 100,and Aromatic 150, and esters, such as butyl acetate, n-propyl acetate,hexyl acetate.

The polyepoxide resin may be reacted with the phosphorous-containingacid or acid derivative before, during, or after reaction of thepolyepoxide resin with the extender and optional monofunctionalreactant. The reaction with the acid or acid derivative, if carried outbefore or after the reaction with the extender, may be carried out at atemperature of from about 50° C. to about 150° C. in solvent, includingany of those already mentioned, or neat. The polyepoxide resin may alsobe reacted with the phosphorous-containing acid or acid derivative andoptionally a monofunctional reactant such as those already described andnot be reacted with an extender.

The amine-functional phosphorylated resin has at least one amine group,and this amine functionality may introduced before or after thephosphorylating reaction. If before, the amine functionality may beintroduced by reaction of the polyepoxide resin with an extender havinga tertiary amine group or with a monofunctional reactant having atertiary amine group. Suitable, nonlimiting examples of extenders andmonofunctional reactants having an amine group include diethanolamine,dipropanolamine, diisopropanolamine, dibutanolamine, diisobutanolamine,diglycolamine, methylethanolamine, dimethylaminopropylamine, andcompounds having a primary amine group that has been protected byforming a ketimine, such as the ketimine of diethylenetriamine.

The polyepoxide resin, extended polyepoxide resin, or epoxide-functionalresin is then reacted with the phosphorous-containing acid or acidderivative, such as any of those mentioned above, to make aphosphorylated resin.

The phosphorylated resin may include monophosphonic acid esters,diphosphonic acid esters, monophosphate ester, diphosphate esters, andtriphosphate esters, as well as combinations of these. In addition, thephosphorylated resin may have one or a plurality of thephosphorous-containing ester groups. The extent of esterification ofphosphorous-containing acid or acid derivative and the number ofphosphorous-containing ester groups incorporated into the resin iscontrolled, inter alia, by the relative equivalents of the reactants. Inone example, from about 1 to about 3 equivalents of resin (based onepoxide and hydroxyl groups) is reacted with each equivalent ofphosphoric acid or phosphoric acid derivative. In another example, fromabout 1 to about 2 equivalents of resin (based on epoxide and hydroxylgroups) is reacted with each equivalent of phosphonic acid or phosphonicacid derivative. The equivalents of the resin reactive groups may alsobe in excess of the equivalents of acid or acid derivative. The resinand phosphoric or phosphonic acid or acid derivative may be mixedtogether and allowed to react until a desired extent of reaction isobtained. In certain embodiments, the weight per epoxide after reactionof an epoxide-functional resin is from about 180 to about 1200.

Other reactants that may be used in addition to the resin andphosphorous-containing acid or acid derivative may include alcohols suchas n-butanol, isopropanol, and n-propanol; glycol ethers such asethylene glycol monobutyl ether, propylene glycol monobutyl ether, andpropylene glycol monopropyl ether; amines such as any of those mentionedabove; water; and combinations of these. These reactants can also beused to react with excess oxirane groups after the reaction of the resinwith the acid or acid derivative.

The amine functionality may be imparted to the phosphorylated resin inone of two ways. In a first way, an amine having at least one activehydrogen reactive with an epoxide group is included as a reactant in thereaction of the epoxide-functional resin and phosphoric acid or sourceof phosphoric acid. In a second way, the reaction product of theepoxide-functional epoxy resin and phosphoric acid (and any furtherreactants) is an epoxide-functional product that is then further reactedwith an amine having at least one active hydrogen reactive with anepoxide group. Examples of suitable amine compounds include, withoutlimitation, dimethylaminopropylamine, N,N-diethylaminopropylamine,dimethylaminoethylamine, N-aminoethylpiperazine, aminopropylmorpholine,tetramethyldipropylenetriamine, methylamine, ethylamine, dimethylamine,dibutylamine, ethylenediamine, diethylenetriamine, triethylenetetramine,dimethylaminobutylamine, diethylaminopropylamine,diethylaminobutylamine, dipropylamine, methylbutylamine, alkanolaminessuch as methylethanolamine, aminoethylethanolamine,aminopropylmonomethylethanolamine, and diethanolamine, diketimine (areaction product of 1 mole diethylenetriamine and 2 moles methylisobutyl ketone), and polyoxyalkylene amines.

In certain embodiments, the phosphorylated resin is anepoxide-functional resin that is reacted with an extender, such any ofthose already mentioned.

The amine-functional phosphorylated resin is used to prepare anelectrocoat coating composition (also known as an electrocoat bath). Ingeneral, a binder is prepared comprising the amine-functionalphosphorylated resin, then the binder is dispersed in an aqueous mediumby salting amine groups present in the binder with an acid.

In certain embodiments, the amine-functional phosphorylated resincomprises from about 0.01 to about 99% by weight of binder in theelectrodeposition coating composition. The amine-functionalphosphorylated resin may comprise from about 0.01 to about 99% by weightof binder, 1 to about 90% by weight of binder, or from about 5 to about80% by weight of binder in the electrodeposition coating composition.The binder may also comprise a crosslinker that reacts with theamine-functional phosphorylated resin during curing of a coating layerformed on a substrate. Suitable examples of crosslinking agents,include, without limitation, blocked polyisocyanates. Examples ofaromatic, aliphatic or cycloaliphatic polyisocyanates includediphenylmethane-4,4′-diisocyanate (MDI), 2,4- or 2,6-toluenediisocyanate (TDI), p-phenylene diisocyanate, tetramethylenediisocyanate, hexamethylene diisocyanate,dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate, mixturesof phenylmethane-4,4′-diisocyanate, polymethylene polyphenylisocyanate,,2-isocyanatopropylcyclohexyl isocyanate, dicyclohexylmethane2,4′-diisocyanate, 1,3-bis(iso-cyanatomethyl)cyclohexane, diisocyanatesderived from dimer fatty acids, as sold under the commercial designationDDI 1410 by Henkel, 1,8-diisocyanato-4-isocyanatomethyloctane,1,7-diisocyanato-4-isocyanato-methylheptane or1-isocyanato-2-(3-isocyanatopropyl)-cyclohexane, and higherpolyisocyanates such as triphenylmethane-4,4′,4″-triisocyanate, ormixtures of these polyisocyanates. Suitable polyisocyantes also includepolyisocyanates derived from these that containing isocyanurate, biuret,allophanate, iminooxadiazinedione, urethane, urea, or uretdione groups.Polyisocyanates containing urethane groups, for example, are obtained byreacting some of the isocyanate groups with polyols, such astrimethylolpropane, neopentyl glycol, and glycerol, for example. Theisocyanate groups are reacted with a blocking agent. Examples ofsuitable blocking agents include phenol, cresol, xylenol,epsilon-caprolactam, delta-valerolactam, gamma-butyrolactam, diethylmalonate, dimethyl malonate, ethyl acetoacetate, methyl acetoacetate,alcohols such as methanol, ethanol, isopropanol, propanol, isobutanol,tert-butanol, butanol, glycol monoethers such as ethylene or propyleneglycol monoethers, acid amides (e.g. acetoanilide), imides (e.g.succinimide), amines (e.g. diphenylamine), imidazole, urea, ethyleneurea, 2-oxazolidone, ethylene imine, oximes (e.g. methylethyl ketoxime),and the like.

The binder may include one or more additional resins. Nonlimitingexamples of suitable additional resins include epoxy resins, polyesters,polyurethanes, vinyl resins such as polyacrylate resins, andpolybutadiene resins. The additional resin may be, for example, any ofthe polyepoxide resins, extended polyepoxide resins, orepoxide-functional resins already mentioned, optionally reacted with acompound having at least one epoxide-reactive group.

In certain embodiments the binder comprises another amine-functionalresin. Nonlimiting examples of suitable amine-functional resins includeamine-functional epoxy resins, polyesters, polyurethanes, vinyl resinssuch as polyacrylate resins, and polybutadiene resins. Amine-functionalepoxy resins may be prepared by reacting any of the polyepoxide resins,extended polyepoxide resins, or epoxide-functional resins alreadymentioned with an amine, including any of those mentioned above assuitable for preparing the amine-functional phosphorylated resin.

Cationic polyurethanes and polyesters may also be used. Such materialsmay be prepared by endcapping with, for example, an aminoalcohol or, inthe case of the polyurethane, the same compound comprising a saltableamine group previously described may also be useful.

Polybutadiene, polyisoprene, or other epoxy-modified rubber-basedpolymers can be used as the resin in the present invention. Theepoxy-rubber can be capped with a compound comprising a saltable aminegroup.

Cationic acrylic resins may be made cathodic by incorporation ofamino-containing monomers, such as acrylamide, methacrylamide,N,N′-dimethylaminoethyl methacrylate tert-butylaminoethyl methacrylate.2-vinylpyridine, 4-vinylpyridine, vinylpyrrolidine or other such aminomonomers. Alternatively, epoxy groups may be incorporated by includingan epoxy-functional monomer in the polymerization reaction. Suchepoxy-functional acrylic polymers may be made cathodic by reaction ofthe epoxy groups with amines according to the methods previouslydescribed for the epoxy resins. The polymerization may also include ahydroxyl-functional monomer. Useful hydroxyl-functional ethylenicallyunsaturated monomers include, without limitation, hydroxyethylmethacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate,hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutylmethacrylate, the reaction product of methacrylic acid with styreneoxide, and so on. Preferred hydroxyl monomers are methacrylic or acrylicacid esters in which the hydroxyl-bearing alcohol portion of thecompound is a linear or branched hydroxy alkyl moiety having from 1 toabout 8 carbon atoms.

The monomer bearing the hydroxyl group and the monomer bearing the groupfor salting (amine for a cationic group or acid or anhydride for anionicgroup) may be polymerized with one or more other ethylenicallyunsaturated monomers. Such monomers for copolymerization are known inthe art. Illustrative examples include, without limitation, alkyl estersof acrylic or methacrylic acid, e.g., methyl methacrylate, ethylacrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate,isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butylmethacrylate, isobutyl acrylate, isobutyl methacrylate, t-butylacrylate, t-butyl methacrylate, amyl acrylate, amyl methacrylate,isoamyl acrylate, isoamyl methacrylate, hexyl acrylate, hexylmethacrylate, 2-ethylhexyl acrylate, decyl acrylate, decyl methacrylate,isodecyl acrylate, isodecyl methacrylate, dodecyl acrylate, dodecylmethacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, substitutedcyclohexyl acrylates and methacrylates, 3,5,5-trimethylhexyl acrylate,3,5,5-trimethylhexyl methacrylate, the corresponding esters of maleic,fumaric, crotonic, isocrotonic, vinylacetic, and itaconic acids, and thelike; and vinyl monomers such as styrene, t-butyl styrene, alpha-methylstyrene, vinyl toluene and the like. Other useful polymerizableco-monomers include, for example, alkoxyethyl acrylates andmethacrylates, acryloxy acrylates and methacrylates, and compounds suchas acrylonitrile, methacrylonitrile, acrolein, and methacrolein.Combinations of these are usually employed.

The binder may also comprise a crosslinker that reacts with theamine-functional resin other than the phosphorylated resin during curingof a coating layer formed on a substrate, or the binder may alsocomprise a crosslinker that reacts with both the amine-functional resinother than the phosphorylated resin and the phosphorylated resin duringcuring of a coating layer formed on a substrate. Optionally, plasticizeror solvents or both can be added to the binder mixture. Nonlimitingexamples of coalescing solvents include alcohols, glycol ethers,polyols, and ketones. Specific coalescing solvents include monobutyl andmonohexyl ethers of ethylene glycol, phenyl ether of propylene glycol,monoalkyl ethers of ethylene glycol such as the monomethyl, monoethyl,monopropyl, and monobutyl ethers of ethylene glycol or propylene glycol;dialkyl ethers of ethylene glycol or propylene glycol such as ethyleneglycol dimethyl ether and propylene glycol dimethyl ether; butylcarbitol; diacetone alcohol. Nonlimiting examples of plasticizersinclude ethylene or propylene oxide adducts of nonyl phenols, bisphenolA, cresol, or other such materials, or polyglycols based on ethyleneoxide and/or propylene oxide. The amount of coalescing solvent is notcritical and is generally between about 0 to 15 percent by weight,preferably about 0.5 to 5 percent by weight based on total weight of theresin solids. Plasticizers can be used at levels of up to 15 percent byweight resin solids.

The binder is emulsified in water in the presence of an acid.Nonlimiting examples of suitable acids include phosphoric acid,phosphonic acid, propionic acid, formic acid, acetic acid, lactic acid,or citric acid. The salting acid may be blended with the binder, mixedwith the water, or both, before the binder is added to the water. Theacid is used in an amount sufficient to neutralize enough of the aminegroups to impart water-dispersibility to the binder. The amine groupsmay be fully neutralized; however, partial neutralization is usuallysufficient to impart the required water-dispersibility. By saying thatthe resin is at least partially neutralized, we mean that at least oneof the saltable groups of the binder is neutralized, and up to all ofsuch groups may be neutralized. The degree of neutralization that isrequired to afford the requisite water-dispersibility for a particularbinder will depend upon its composition, molecular weight of the resins,weight percent of amine-functional resin, and other such factors and canreadily be determined by one of ordinary skill in the art throughstraightforward experimentation.

The binder emulsion is then used in preparing an electrocoat coatingcomposition (or bath). The electrocoat bath may contain no pigment so asto produce a colorless or clear electrodeposited coating layer, but theelectrocoat bath usually includes one or more pigments, separately addedas part of a pigment paste, and may contain any further desiredmaterials such as coalescing aids, antifoaming aids, and other additivesthat may be added before or after emulsifying the resin. Conventionalpigments for electrocoat primers include titanium dioxide, ferric oxide,carbon black, aluminum silicate, precipitated barium sulfate, aluminumphosphomolybdate, strontium chromate, basic lead silicate or leadchromate. The pigments may be dispersed using a grind resin or a pigmentdispersant. The pigment-to-resin weight ratio in the electrocoat bathcan be important and should be preferably less than 50:100, morepreferably less than 40:100, and usually about 10 to 30:100. Higherpigment-to-resin solids weight ratios have been found to adverselyaffect coalescence and flow. Usually, the pigment is 10-40 percent byweight of the nonvolatile material in the bath. Preferably, the pigmentis 15 to 30 percent by weight of the nonvolatile material in the bath.Any of the pigments and fillers generally used in electrocoat primersmay be included. Inorganic extenders such as clay and anti-corrosionpigments are commonly included.

The electrodeposition coating compositions can contain optionalingredients such as dyes, flow control agents, plasticizers, catalysts,wetting agents, surfactants, UV absorbers, HALS compounds, antioxidants,defoamers and so forth. Examples of surfactants and wetting agentsinclude alkyl imidazolines such as those available from Ciba-GeigyIndustrial Chemicals as AMINE C® acetylenic alcohols such as thoseavailable from Air Products and Chemicals under the tradename SURFYNOL®.Surfactants and wetting agents, when present, typically amount to up to2 percent by weight resin solids.

Curing catalysts such as tin catalysts can be used in the coatingcomposition. Typical examples are without limitation, tin and bismuthcompounds including dibutyltin dilaurate, dibutyltin oxide, and bismuthoctoate. When used, catalysts are typically present in amounts of about0.05 to 2 percent by weight tin based on weight of total resin solids.

The electrocoat coating composition is electrodeposited onto a metallicsubstrate. The substrate may be, as some nonlimiting examples,cold-rolled steel, galvanized (zinc coated) steel, electrogalvanizedsteel, stainless steel, pickled steel, GALVANNEAL® GALVALUME®, andGALVAN® zinc-aluminum alloys coated upon steel, and combinations ofthese. Nonlimiting examples of useful non-ferrous metals includealuminum, zinc, magnesium and alloys of these. The electrodeposition ofthe coating preparations according to the invention may be carried outby known processes. The electrodeposition coating composition may beapplied preferably to a dry film thickness of 10 to 35 μm. In oneembodiment of the method, the electrically conductive substrate isunphosphated; that is, it is free of a phosphate pre-treatment Thearticle coated with the composition of the invention may be a metallicautomotive part or body. A method of coating an electrically conductivesubstrate, such as a metal automotive vehicle body or part, comprisesplacing an electrically conductive substrate, cleaned but preferably notgiven a phosphate pre-treatment, into the electrocoat coatingcomposition and, using the electrically conductive substrate as thecathode, passing a current through the electrocoat coating compositioncausing a coating layer to deposit onto the electrically conductivesubstrate. After application, the coated article is removed from thebath and rinsed with deionized water. The coating may be cured underappropriate conditions, for example by baking at from about 275° F. toabout 375° F. for between about 15 and about 60 minutes, before applyingan additional coating layer over the electrodeposited coating layer.

An automotive vehicle body may be electrocoated. The automotive vehiclebody is cleaned, and the cleaned metal automotive vehicle body iselectrocoated with an aqueous electrodeposition coating compositioncomprising the phosphorylated resin.

One or more additional coating layers, such as a spray-appliedprimer-surfacer, single topcoat layer, or composite color coat(basecoat) and clearcoat layer, may be applied over the electrocoatlayer. A single layer topcoat is also referred to as a topcoat enamel.In the automotive industry, the topcoat is typically a basecoat that isovercoated with a clearcoat layer. A primer surfacer and the topcoatenamel or basecoat and clearcoat composite topcoat may be waterborne,solventborne, or a powder coating, which may be a dry powder or anaqueous powder slurry.

The composite coating of the invention may have, as one layer, a primercoating layer, which may also be termed a primer-surfacer or fillercoating layer. The primer coating layer can be formed from asolventborne composition, waterborne composition, or powder composition,including powder slurry composition. The primer composition preferablyhas a binder that is thermosetting, although thermoplastic binders arealso known. Suitable thermosetting binders may have self-crosslinkingpolymers or resins, or may include a crosslinker reactive with a polymeror resin in the binder. Nonlimiting examples of suitable binder polymersor resins include acrylics, polyesters, and polyurethanes. Such polymersor resins may include as functional groups hydroxyl groups, carboxylgroups, anhydride groups, epoxide groups, carbamate groups, aminegroups, and so on. Among suitable crosslinkers reactive with such groupsare aminoplast resins (which are reactive with hydroxyl, carboxyl,carbamate, and amine groups), polyisocyanates, including blockedpolyisocyanates (which are reactive with hydroxyl groups and aminegroups), polyepoxides (which are reactive with carboxyl, anhydride,hydroxyl, and amine groups), and polyacids and polyamines (which arereactive with epoxide groups). Examples of suitable primer compositionsare disclosed, for example, in U.S. Pat. Nos. 7,338,989; 7,297,742;6,916,877; 6,887,526; 6,727,316; 6,437,036; 6,413,642; 6,210,758;6,099,899; 5,888,655; 5,866,259; 5,552,487; 5,536,785; 4,882,003; and4,190,569, each assigned to BASF and each incorporated herein byreference.

The primer coating composition applied over the electrocoat primer maythen be cured to form a primer coating layer. The electrocoat primer maybe cured at the same time as the primer coating layer in a process knownas “wet-on-wet” coating.

A topcoat composition may be applied over the electrocoat layer orprimer coating layer and, preferably, cured to form a topcoat layer. Ina preferred embodiment, the electrocoat layer or primer layer is coatedwith a topcoat applied as a color-plus-clear (basecoat-clearcoat)topcoat. In a basecoat-clearcoat topcoat, an underlayer of a pigmentedcoating, the basecoat, is covered with an outer layer of a transparentcoating, the clearcoat. Basecoat-clearcoat topcoats provide anattractive smooth and glossy finish and generally improved performance.

Crosslinking compositions are preferred as the topcoat layer or layers.Coatings of this type are well-known in the art and include waterbornecompositions, solventborne compositions, and powder and powder slurrycompositions. Polymers known in the art to be useful in basecoat andclearcoat compositions include, without limitation, acrylics, vinyls,polyurethanes, polycarbonates, polyesters, alkyds, and polysiloxanes.Acrylics and polyurethanes are among preferred polymers for topcoatbinders. Thermoset basecoat and clearcoat compositions are alsopreferred, and, to that end, preferred polymers comprise one or morekinds of crosslinkable functional groups, such as carbamate, hydroxy,isocyanate, amine, epoxy, acrylate, vinyl, silane, acetoacetate, and soon. The polymer may be self-crosslinking, or, preferably, thecomposition may include a crosslinking agent such as a polyisocyanate oran aminoplast resin. Examples of suitable topcoat compositions aredisclosed, for example, in U.S. Pat. Nos. 7,375,174; 7,342,071;7,297,749; 7,261,926; 7,226,971; 7,160,973; 7,151,133; 7,060,357;7,045,588; 7,041,729; 6,995,208; 6,927,271; 6,914,096; 6,900,270;6,818,303; 6,812,300; 6,780,909; 6,737,468; 6,652,919; 6,583,212;6,462,144; 6,337,139; 6,165,618; 6,129,989; 6,001,424; 5,981,080;5,855,964; 5,629,374; 5,601,879; 5,508,349; 5,502,101; 5,494,970;5,281,443; and, each assigned to BASF and each incorporated herein byreference.

The further coating layers can be applied to the electrocoat coatinglayer according to any of a number of techniques well-known in the art.These include, for example, spray coating, dip coating, roll coating,curtain coating, and the like. For automotive applications, the furthercoating layer or layers are preferably applied by spray coating,particularly electrostatic spray methods. Coating layers of one mil ormore are usually applied in two or more coats (passes), separated by atime sufficient to allow some of the solvent or aqueous medium toevaporate, or “flash,” from the applied layer. The flash may be atambient or elevated temperatures, for example, the flash may use radiantheat. The coats as applied can be from 0.5 mil up to 3 mils dry, and asufficient number of coats are applied to yield the desired finalcoating thickness.

A primer layer may be cured before the topcoat is applied. The curedprimer layer may be from about 0.5 mil to about 2 mils thick, preferablyfrom about 0.8 mils to about 1.2 mils thick.

Color-plus-clear topcoats are usually applied wet-on-wet. Thecompositions are applied in coats separated by a flash, as describedabove, with a flash also between the last coat of the color compositionand the first coat the clear. The two coating layers are then curedsimultaneously. Preferably, the cured basecoat layer is 0.5 to 1.5 milsthick, and the cured clear coat layer is 1 to 3 mils, more preferably1.6 to 2.2 mils, thick.

Alternatively the primer layer and the topcoat can be applied“wet-on-wet.” For example, the primer composition can be applied, thenthe applied layer flashed; then the topcoat can be applied and flashed;then the primer and the topcoat can be cured at the same time. Again,the topcoat can include a basecoat layer and a clearcoat layer appliedwet-on-wet. The primer layer can also be applied to an uncuredelectrocoat coating layer, and all layers cured together.

The coating compositions described are preferably cured with heat.Curing temperatures are preferably from about 70° C. to about 180° C.,and particularly preferably from about 170° F. to about 200° F. for atopcoat or primer composition including an unblocked acid catalyst, orfrom about 240° F. to about 275° F. for a topcoat or primer compositionincluding a blocked acid catalyst. Typical curing times at thesetemperatures range from 15 to 60 minutes, and preferably the temperatureis chosen to allow a cure time of from about 15 to about 30 minutes. Ina preferred embodiment, the coated article is an automotive body orpart.

The invention is further described in the following example. The exampleis merely illustrative and does not in any way limit the scope of theinvention as described and claimed. All parts are parts by weight unlessotherwise noted.

EXAMPLES

Preparation A: Preparation of Amine-Functional Phosphorylated EpoxyResin

A reactor equipped with an agitator and reflux condenser is charged with25.85 parts by weight of normal butanol, 10.20 parts by weight ofethylene glycol monobutyl ether, and 55.62 parts by weight of thediglycidyl ether of Bisphenol A. The reactor contents are stirred forabout 5 minutes followed by addition of a 3.11 parts of diethanolamine.The resulting mixture is heated to 77° F. (25° C.); heat is thendiscontinued, and the reaction mixture is allowed to exotherm. Thetemperature of the reaction continues to increase to 120.2-122° F.(49-50° C.). The reaction mixture is maintained at 140-149° F. (60-65°C.) for 30 minutes. To the reactor is added a mixture of 4.261 parts byweight phosphoric acid (75% aqueous) and 1.77 parts by weight normalbutanol. During the addition the temperature is held to below 102.2° F.(49° C.). The reaction mixture is stirred for about 15 minutes, then thereactor is heated to 220-250° F. (104.4-121.1° C.). Reaction iscontinued until the weight per epoxide of the product is 800 or greater.Then, deionized water is added in a first portion of 0.899 parts byweight, and the reaction mixture is maintained at 220-250° F.(104.4-121.1° C.) for one hour. A second portion of deionized water,0.70 parts by weight, is then added to the reaction mixture. Again thereaction mixture is maintained at 220-250° F. (104.4-121.1° C.) for onehour. A final portion of deionized water, 0.70 parts by weight, is thenadded to the reaction mixture. Again the reaction mixture is maintainedat 220-250° F. (104.4-121.1° C.) for one hour. The product is thendiluted with normal butanol to 72% nonvolatile by weight.

Preparation B: Preparation of Binder Emulsion with Amine-FunctionalPhosphorylated Epoxy Resin

The following materials are combined in a 5-L flask with an associatedheating mantle: diglycidyl ether of bisphenol A (DGEBA), (18.03 parts),bisphenol A (BPA), (4.1 parts), phenol (1.41 parts), and propyleneglycol n-butyl ether (0.36 parts).

While stirring, the temperature is raised to 257° F. (125° C.).Subsequently, triphenylphosphine (0.04 parts) is added and the exothermis recorded as 392° F. (200° C.). The mixture is then allowed to cool to275° F. (135° C.), and a weight per epoxide (WPE) determination(target=525±25) is conducted and is 526. After cooling to 194° F. (90°C.) and turning off the heating mantle, 2.36 parts of PLURACOL® 710R(sold by BASF Corporation) is added, then 1.73 parts of diethanolamineis introduced and the exotherm is recorded as 239° F. (115° C.). Thereaction mixture is allowed to stir for an additional 30 minutes at 221°F. (105° C.) after reaching exotherm. After stirring for 30 minutes,3-dimethylaminopropylamine is added at 221° F. (105° C.) (0.84 parts),and the exotherm is recorded as 280.4° F. (138° C.). The mixture isstirred for an additional hour. A crosslinker (a blocked isocyanatebased on polymeric MDI and monofunctional alcohols) (13.6 parts) isadded. The mixture is stirred for 30 minutes at 221-230° F. (105-110°C.). Preparation A, the amine-functional phosphorylated epoxy resin,(6.47 parts) is added and the mixture is stirred for an additional 15minutes at 221-230° F. (105-110° C.).

After achieving a homogeneous mixture, the resins and crosslinker blendis added to an acid/water mixture, under constant stirring, of deionizedwater (34.95 parts) and formic acid (88%) (0.62 parts). After thoroughlymixing all components using a metal spatula, the solids are furtherreduced by addition of water (18.55 parts). A flow-additive package(2.51 parts) is added to the acid mixture.

Preparation C: Grinding Resin Solution having Tertiary Ammonium Groups

In accordance with EP 0 505 445 B1, an aqueous-organic grinding resinsolution is prepared by reacting, in the first stage, 2598 parts ofbisphenol A diglycidyl ether (epoxy equivalent weight (EEW) 188 g/eq),787 parts of bisphenol A, 603 parts of dodecylphenol, and 206 parts ofbutyl glycol in a stainless steel reaction vessel in the presence of 4parts of triphenylphosphine at 130° C. until an EEW (epoxy equivalentweight) of 865 g/eq is reached. In the course of cooling, the batch isdiluted with 849 parts of butyl glycol and 1534 parts of D.E.R® 732(polypropylene glycol diglycidyl ether, DOW Chemical, USA) and isreacted further at 90° C. with 266 parts of 2,2′-aminoethoxyethanol and212 parts of N,N-dimethylaminopropylamine. After 2 hours, the viscosityof the resin solution is constant (5.3 dPas; 40% in SOLVENON® PM(methoxypropanol, BASF/Germany); cone and plate viscometer at 23° C.).It is diluted with 1512 parts of butyl glycol and the base groups arepartly neutralized with 201 parts of glacial acetic acid, and theproduct is diluted further with 1228 parts of deionized water anddischarged. This gives a 60% strength aqueous-organic resin solutionwhose 10% dilution has a pH of 6.0. The resin solution is used in directform for paste preparation.

Preparation D: Pigment Paste

A premix is first formed from 125 parts of water and 594 parts of thegrinding resin of Preparation C. Then 7 parts of acetic acid, 9 parts ofTetronic® 901, 8 parts of carbon black, 547 parts of titanium dioxideTI-PURE® R 900 (DuPont, USA), 44 parts of di-n-butyl tin oxide, 47 partsof bismuth subsalicylate, and 120 parts of ASP200 clay (Langer &Co./Germany) are added. The mixture is predispersed for 30 minutes undera high-speed dissolver stirrer. The mixture is subsequently dispersed ina small laboratory mill (Motor Mini Mill, Eiger Engineering Ltd, GreatBritain) until it measures a Hegmann fineness of less than or equal to12 μm and is adjusted to solids content with additional water. Theobtained pigment paste has solids content: 67% by weight (1 hour at 110°C.).

Example 1

A bath was prepared by combining 1096.1 parts Preparation B, 147.3 partspreparation D, and 1256.6 parts deionized water. The water andPreparation B resin emulsion are combined in a container with constantstirring, and Preparation D is added with stirring. The bath solidcontents are 19% by weight.

Example 1 is tested by coating both phosphated and bare cold rolledsteel 4-inch-by-6-inch test panels at 100 -225 volts (0.5 ampere) inExample 1 at bath temperatures from 88-98° F. (31-36.7° C.) for 2.2minutes and baking the coated panels for 28 minutes at 350° F. (177°C.). The deposited, baked coating has a filmbuild of about 0.8 mil (20μm). Three panels were coated for each temperature and substrate.

Control

Control panels were prepared as described for Example 1 but usingU32AD500 (commercial product sold by BASF Corporation).

After baking, panels are tested as follows or further coated with a topcoat and then tested.

Description of Corrosion test GMW15288: Each panel is scribed directlydown the middle and tested the description is as follows: On a Monday,each panel is held at 60° C. for one hour in an air-circulating oven andis then subjected to a cold cabinet at −25° C. for 30 minutes.Following, the panels are immersed for 15 minutes in a 5 wt. % NaClsolution in water (saline solution). After removal, the panels areallowed to air dry for 75 minutes at room temperature. The panels arethen transferred to a humidity cabinet (60° C., 85% humidity) with anair flow not exceeding 15 m/ft across the panel and held for 21 hours.From Tuesday to Friday, the panels are immersed again in the salinesolution for 15 minutes, allowed to air dry to 75 minutes at roomtemperature, and then returned to the humidity cabinet (22 hours). OnSaturday and Sunday the panels remain in the humidity cabinet. Theentire exposure sequence from Monday to the following Monday constitutes5 cycles. The test is then repeated for a total of 20 cycles. Aftercompletion, each panel is rinsed with water and scraped with a metalspatula. The corrosion is measured as the average of scribe width ofselected points along the scribe length.

Description SAE J2334 DEC2003: After baking, each panel is scribeddirectly down the middle and tested as follows. For 6 hours the testpanels are subjected to 100% RH (relative humidity) at 50° C., 15 minutesalt solution dip at ambient conditions, where the salt solutionconsists of 0.5% NaCl, 0.1% CaCl₂ and 0.075% NaHCO₃. For the remaining17 hours and 45 minutes the test panels are placed at 60° C. and 50% RH.The cycle is repeated 20 times. After completion, each panel is rinsedwith water and scraped with a metal spatula. The corrosion is measuredas the average of scribe width of selected points along the scribelength.

The top coating process for each of the following systems were preformedby hand application using the following products/procedure:

Integrated Process SB (solventborne):

-   U28AU227 (commercial product sold by BASF Corporation) applied to    0.9 mils followed by 5-minute, room-temperature flash-   E38WU466L (commercial product sold by BASF Corporation) applied to    0.9 mils followed by 8 minute, room-temperature flash-   R10CG392 (commercial product sold by BASF Corporation) applied to    1.8 mils followed by 8-minutes, room-temperature flash, followed by    5 minutes at 200° F., followed by 17 minutes at 285° F.

Waterborne Basecoat/2K Clearcoat Process:

-   U28WW554 (commercial product sold by BASF Corporation) applied to    1.0 mils, flash 5 minutes a room temperature followed by 30 minutes    at 265° F.-   E54WW301 (commercial product sold by BASF Corporation) applied to    0.5 mils flash 5 minutes at 150° F.-   E211WW328 (commercial product sold by BASF Corporation) applied to    0.4 mils flash 5 minutes at 150° F.-   E10CG081 (commercial product sold by BASF Corporation) applied to    1.8 mils, flashed 10 minutes at room temperature followed by 10    minutes at 180° F. followed by 25 minutes at 255° F.

Powder Topcoat Process:

-   960KM0002 (commercial product sold by BASF Corporation) applied to    2.0 mils and cured 20 minutes at 340° F.

Humidity test was performed in accordance with ASTM D3359 and chiptesting was performed in accordance with GMW 14700.

Results of testing are shown in the following Tables 1-3.

TABLE 1 Corrosion test GMW15288 Ave mm Scribe width after 20 CyclesGMW15288 Substrate Control Example 1 Cold Roll Steel B958 P90 0.9 1.6Cold Roll Steel Clean Bare Unpolished 16.9 3.5 Electrogalvanized Zn Bare0.3 0.7 Electrogalvanized B958 P90 2.9 2.2 Zinc/Iron Bare 0.3 0.3Zinc/Iron B958 P90 0.3 0.3

TABLE 2 SAE J2334 Corrosion on Topcoated Panels mm Scribe creep after 20Cycles J2334 Control with Integrated Process SB 19 Example 1 withIntegrated Process SB 13 Control with WBBC/2K 13 Example A with WBBC/2K6

TABLE 3 Chip and Humidity on Topcoated Panels Integrated Waterborne/Urethane Process SB 2K Powder Topcoat Humidity Humidity Humidity Adhe-Adhe- Adhe- Chip* sion** Chip* sion** Chip* sion** Exam- 8 5A 9 5A 9 5Aple A Control 8 5A 9 5A 9 5A *GMW 14700 (3 pts; −20 F.; 90 degrees)**ASTM D3359

Throwpower was tested in accordance with FORD Laboratory Test method B1120-02 Results are shown in Table 4.

TABLE 4 Throwpower cm from Filmbuild (microns) @ bottom specified cmthrow of panel Control Example A 1 19.81 18.54 2 19.3 16.76 4 17.7814.73 6 16 12.7 8 12.95 11.18 10 10.92 8.64 12 7.87 6.35 14 4.83 4.83 162.54 3.56 18 0.76 1.52 20 0 0

The description is merely exemplary in nature and, thus, variations thatdo not depart from the gist of the disclosure are a part of theinvention. Variations are not to be regarded as a departure from thespirit and scope of the disclosure.

1. An aqueous coating composition comprising a binder, the bindercomprising amine-functional phosphorylated resin.
 2. An aqueous coatingcomposition according to claim 1, wherein the resin is an epoxy resin.3. An aqueous coating composition according to claim 1, wherein thephosphorylated resin comprises a monophosphate ester group, amonophosphonic acid ester group, or both.
 4. An aqueous coatingcomposition according to claim 1, wherein the phosphorylated resincomprises a diphosphate ester group, a diphosphonic acid ester group, orboth.
 5. An aqueous coating composition according to claim 1, whereinthe phosphorylated resin comprises, on average, more than onephosphorous atom per molecule.
 6. An aqueous coating compositionaccording to claim 2, wherein the coating composition is free of epoxyresins other than the phosphorylated epoxy resin.
 7. An aqueous coatingcomposition according to claim 1, wherein the binder comprises fromabout 0.01 to about 99% by weight of the phosphorylated resin.
 8. Anaqueous coating composition according to claim 2, wherein the epoxyresin is based on bisphenol A.
 9. An aqueous coating compositionaccording to claim 1, wherein the binder further comprises a secondamine-functional resin.
 10. An aqueous coating composition according toclaim 1, wherein the amine-functional phosphorylated resin is an acrylicresin.
 11. An aqueous coating composition according to claim 1, whereinthe phosphorylated resin comprises a triphosphate ester group.
 12. Anaqueous coating composition comprising an amine-functional resin havingat least one group

in which X is a hydrogen, a monovalent hydrocarbon, an alkyl group, anaryl group, an alkylaryl group, an arylalkyl group, or an oxygen atomhaving a single covalent bond to the phosphorous atom, and each oxygenatom has a covalent bond to a hydrogen atom, an alkyl group, an arylgroup, an alkylaryl group, an arylalkyl group, or the amine-functionalresin, with the caveat that at least one oxygen atom has a covalent bondto the amine-functional resin.
 13. An aqueous coating compositionaccording to claim 12, further comprising a crosslinker reactive withthe amine-functional resin.
 14. An aqueous coating composition accordingto claim 13, further comprising a second amine-functional resin reactivewith the crosslinker, wherein the second amine-functional resin does notinclude phosphorous-containing groups.
 15. A method of coating a metalautomotive vehicle body, comprising: (a) cleaning the metal automotivevehicle body; (b) placing the cleaned metal automotive vehicle body intoan aqueous coating composition according to claim 1; (c) connecting themetal automotive vehicle body as a cathode in an electric circuit andpassing a current through the aqueous electrodeposition coatingcomposition to deposit a coating layer onto the metal automotive vehiclebody.
 16. A method of coating an electrically conductive substrateaccording to claim 15, wherein the metal automotive vehicle body is freeof a phosphate pre-treatment.
 17. A method of coating an electricallyconductive substrate according to claim 15, wherein the phosphorylatedresin comprises a phosphate ester of a polyepoxide resin, a phosphonicacid ester of a polyepoxide resin, or a combination thereof.
 18. Amethod of coating an electrically conductive substrate according toclaim 15, wherein the phosphorylated resin comprises a diphosphate esterof a polyepoxide resin, a diphosphonic acid ester of a polyepoxideresin, or a combination thereof.
 19. A method of coating an electricallyconductive substrate according to claim 15, wherein the phosphorylatedresin comprises, on average, more than one phosphorous atom permolecule.
 20. A method of coating an electrically conductive substrateaccording to claim 15, wherein the phosphorylated resin is an epoxyresin.
 21. A method of coating an electrically conductive substrateaccording to claim 15, wherein the phosphorylated epoxy resin is atleast about 5 weight percent of the binder.
 22. A coated substrateprepared according to the method of claim 15.